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Which embolization approach is preferred for liver metastases from well differentiated neuroendocrine tumors?

1 Answer
Mednet MemberInvited Expert
Medical Oncology · UH Seidman Cancer Center, Case Western Reserve University
Answered on · Updated on
  • Treatment options for metastatic GEP-NETs have evolved in recent years including PRRT which definitely affects our decisions for when and who will be eligible for liver-directed therapies (LDTs). In general, LDTs are appropriate for patients with G1/2 well diff. diffuse, unresectable liver metastases whose tumors are predominantly metastatic to the liver with no extrahepatic mets, and they are not eligible for cytoreduction (70 or 90%). The most commonly used LDTs are intra-arterial embolization techniques such as TAE (Transarterial embolization) using either hepatic artery bland embolization, radioembolization using Y90 spheres, or TACE (Transarterial chemoembolization). Other ablation techniques that are less commonly used include cryoablation, alcohol ablation, and radiofrequency ablation (RFA).
  • TAE with bland embolization: RR between 48-73%, most side effects due to ischemic hepatitis include abdominal pain, nausea, fever, fatigue, transaminitis. Bland is contraindicated in patients with liver dysfunction, moderate to severe ascites, and portal venous thrombosis.
  • TAE with Y90 spheres: RR between 45-63% with median survival of 28-70 months. Usually less painful, but patients can have nausea, fatigue, liver abscess, and rarely radiation enteritis or carcinoid crisis features in those with higher disease burden. 
  • TACE: RR between 33-67%, limited data showing a trend for better survival but also has more side effects including elevated mortality in those with higher liver tumor burden of greater 50-70% secondary to liver failure so maybe, we should avoid it in this subgroup of patients. 
  • Given the lack of prospective trials, complexity of these patients, and emerging of novel therapies such as PRRT and TAT treatment, decisions should be made in a multidisciplinary setting involving input from experienced medical oncologists, hepatologists, radiation oncologists, IR, and surgical oncologists to best determine the best treatment. 
  • Several points we need to keep in mind: 
    1. There are no randomized studies comparing TAE to TACE techniques. Several retrospective studies showed marginal differences in TAE versus TACE with a trend towards better survival with TACE. These data are limited with unclear evidence to favor TACE over TAE without prospective trials. Currently, there is an ongoing trial comparing bland to TACE and we are waiting for final results. So currently with lack of data to favor one over the other, it seems to depend more on which one is your institutional favorable technique. 
    2. We see more pain with bland, and more liver abscess with Y90. This is just clinical practice observation.
    3. There is limited data raising the concern for increased liver toxicity in patients who had previously TAE with Y90 and then PRRT. This needs to be confirmed with larger trials as recently there is data from HEPAR PLuS trial which used Holmium Embolization Particles for Arterial Radiotherapy plus PRRT that lead to an improved response rate without significant additional side-effects. Until we have more data, we may consider doing more selective Y90 or even choose to do bland embolization for those who will be qualified for PRRT in the future.